How would you demonstrate the secondary affects of roll?

[JulieFlyGal]

The secondary affect of roll is yaw, but how would you best demonstrate this to a student? I've found this very hard to eyeball myself, let alone explain it to a student.

[DB6]

Raise the nose slightly above the horizon, roll the aircraft to about 30-40 degrees bank, and watch as the nose drops sideways back through the horizon.

[Karl Bamforth]

Errrrmmmmmmm wouldn't secondary affects of roll produce a yaw opposite to the roll ?

The way I was taught was to line up the nose with a feature, (we used a church steeple) then roll left and watch the nose move right compared to the feature. Similar the other way.
My instructor made me practice reversing the roll left and right while lined up with the feature as a way of practicing to co-ordinate rudder.

[Dendmar]

"Errrrmmmmmmm wouldn't secondary affects of roll produce a yaw opposite to the roll ?"

Have a re-read of your Principles of Flight - you have confused secondary effect of Roll with Adverse Yaw. DB6 has described a good way of demonstrating this effect.

[Whopity]

The way I was taught was to line up the nose with a feature, (we used a church steeple) then roll left and watch the nose move right compared to the feature. Similar the other way.

But adverse Yaw is a Primary effect caused by movement of the control surfaces. The secondary or further effect, is caused by the roll not by the control surfaces.

DB6 has it in one.

[EladElap]

Yes, adverse aileron yaw does happen... but when talking about the secondary effect of the ailerons, remember the following. Demonstrate a 30 degree angle of bank by moving the yoke left/right. The primary effect is roll... then due to the fact that lift is now no longer directly opposing lift, you get slip... this slipping results in a weathercock/fuselage effect. What happens now is that because you have more fuselage area behind the CofP the aircraft will yaw in the direction of the roll.

Adverse aileron yaw i.e. yaw out of turn is completely different to the secondary effect of the ailerons and they are caused by two completely different reasons.

Hope this helps

[Karl Bamforth]

Oooooooooooooohhhhhhhhhh :mad:

My apologies gentlemen, I missunderstood the question. Thought he was asking about adverse yaw. :uhoh:

I really must stop work and concentrate harder when doing important things like responding to Pprune.

Thank you for spotting my mistake. :ok:

[ksa5223]

The secondary effects of Yaw is Roll. :}

[JulieFlyGal]

Thank you for all your replies, especially DB6. I will try that next time and see how it goes.

The secondary effects of Yaw is Roll.

Yes, demonstration of the secondary effects of Yaw is easy. Kick the rudder in with some force and the nose will yaw about the normal axis, followed by a roll about the longitudinal axis . :ok:

[VFE]

What happens now is that because you have more fuselage area behind the CofP the aircraft will yaw in the direction of the roll.
Is that so?

I always understood that when bank is applied by use of ailerons, the aircraft sideslips towards the lower wing. As a result of this sideslip the sideways pressure of air upon the keel surface of the fuselage behind the centre of gravity will tend to yaw the aircraft into the direction of the slip.

VFE.

[homeguard]

Why is it argued that only the yaw resulting from slip is a secondary effect?

Adverse yaw is not always only as a result of 'adverse aileron drag'. Much has been done in aircraft design to eliminate aileron drag. Cessna introduced the 'Frise' concept in addition to 'differential' methods of eliminating adverse drag many years ago and although adverse aileron drag remains it can be minor. While each method only reduces the degree of adverse drag they do make the secondary effect of adverse yaw less of a consideration. The adverse yaw resulting from skid is still very marked though and must be understood and the skill of prevention practiced.

During roll the result of skid should be considered and in my view the original poster is quite correct to consider it. So we have two secondary effects from roll; Yaw resulting from slip and yaw resulting from skid (in addition to any aileron yaw). Slip is prevented by the the use of elevator (maintaining height) but the effects resulting from skid (in addition to any aileron drag) are prevented by the use of rudder simultaneous with the correct proportional use of aileron.

It follows then that both 'secondary effects must be demonstrated and understood.Too often I discover that the secondary effect resulting resulting from slip is covered and understood but an ignorance of the yaw resulting from skid continues. The lack of understanding of adverse yaw leads to over control and in-appropiate use of aileron, paricularly at the slower speeds during the approach, but not only.

[DB6]

Homeguard - possibly correct but a shade too complex at this stage; remember we are talking Effects of Controls 1 here. All that is required is to show Bloggs that if you deflect the ailerons the aircraft first rolls, then yaws for reasons described above (and if left uncorrected a spiral dive will result). Adverse aileron yaw can be demonstrated later - normally during CT&D 1 when teaching how to roll in and out of turns - but will just confuse matters at this stage.
JulieFlyGal - when demonstrating, a good technique is to just use one finger under the yoke (or against the stick) to avoid applying back pressure, as this can mask the effect. To explain to the student, mention how a dart will fall point-down when dropped; same principle but with wings to complicate things a bit.

[homeguard]

DB6, it is not possibly correct, it is correct. The effect from skid is no more complex to understand than the effects resulting from slip.

Demonstrating both does not confuse it illuminates. After all, in the sequence of events once aileron is applied what happens first. Slip or adverse yaw?

Not to be forgotten is that a short period, after an angle of bank has been achieved, will elapse, owing to inertia, before the slip develops and yet after that before the further effect of yaw becomes apparent. The effects of adverse yaw take place almost immediately and during the rolling motion and will be the first effect that the student will experience. Ignoring some elements at the early stage only leads to confusion.

For instance the cause of the yaw from slip is easily cured by the use of elevator to maintain height. No more slip therefore no more yaw. It is too easy to leave the student confused: you say one thing but another differnet control has the desired effect.

[Keygrip]

Slight thread drift, but unless you have QFE set and are demonstrating this over perfectly flat land would the elevator input not be used for maintaining "altitude"?

May as well get them used to the correct terms, ignoring some elements at the early stage only leads to confusion.

Granted, you could maintain *sufficient" height to avoid a CFIT report - but I doubt you would MAINTAIN any given HEIGHT.

[bookworm]

Have a re-read of your Principles of Flight - you have confused secondary effect of Roll with Adverse Yaw.

Isn't it about time the instructional community stopped using arbitrary and ambiguous terms which are bound to confuse students? I can't find a definition of "secondary effects of flight controls" in any aerodynamics or flight mechanics text -- "secondary flight controls" are sometimes defined, but there's never a distinction between primary and secondary effects. They just get on with defining the stability derivatives. Wikipedia, FWIW, currently classes (http://en.wikipedia.org/wiki/Longitudinal_axis#Secondary_effects_of_controls) adverse yaw as the "secondary effect" of aileron.

The problem is that it's more complex than just "primary" and "secondary" because it depends on where you start and what else is going on.

There's an effect of aileron deflection itself in creation of a yawing moment through "adverse yaw".

There's an effect of roll rate in creation of a yawing moment through differential induced drag on the wings due to different AoAs.

There's an effect of bank angle in creation of a yawing moment through creation of a sideslip angle and thus the effect of directional stability, if the sideslip is permitted to persist.

I'm also at a loss as to why you'd choose to demonstrate yaw in the vertical:

Raise the nose slightly above the horizon, roll the aircraft to about 30-40 degrees bank, and watch as the nose drops sideways back through the horizon.

Surely the student associates yaw with a change in heading. Why not roll the aircraft to a shallow bank angle and watch the change in heading, which is almost entirely yaw?

[VFE]

Good luck explaining all that in a 15 minute brief Bookworm!

Raise the nose slightly above the horizon, roll the aircraft to about 30-40 degrees bank, and watch as the nose drops sideways back through the horizon.

You don't need to be a genius to realise that the above demonstration would work well set against the horizon which is the datum for exercise 4. What are you babbling on about with regards "the vertical"?? Trying to be clever?? :rolleyes:

VFE.

[Keygrip]

book - I was always taught to say "FURTHER effect" rather than "secondary effect".

Was also taught that the results of control surface movements are to be viewed and referred to as relative to the pilot.

The fact that the nose of the aircraft is seen, in DB6's method, above and below the horizon does not represent movement in "the vertical". As VFE says - it's a potential 'datum' from which to observe that the movement does occur.

How do you address the third portion - that unchecked roll/yaw results in a spiral dive?

[BEagle]

Lord love a duck, it isn't that hard...

Further effect of roll is sideslip, fin generates yaw. Teach with a little aeroplane model.

To demo, roll gently to about 30 deg bank and get the student to watch the relative 'downhill' movement of the nose.

Roll>sideslipe>yaw>roll>more sideslip>more yaw...and eventually a spiral descent. Demo on EoC1.

Adverse aileron yaw can be demonstrated by entering a normal 30 deg AoB turn, then getting the student to watch the motion of the nose as you roll rapidly to wings level. Much easier to demo it that way than trying to roll rapidly into a turn! But to be honest, that's a bit of a nicety as the student should, by the time such information becomes relevant, know that the ball must be kept in the middle!

[bookworm]

Good luck explaining all that in a 15 minute brief Bookworm!

But you explain it all anyway, VFE -- well you might not mention the yaw due to roll rate but you certainly describe the other two, don't you? What I'm haggling about is the labels you use.

The fact that the nose of the aircraft is seen, in DB6's method, above and below the horizon does not represent movement in "the vertical". As VFE says - it's a potential 'datum' from which to observe that the movement does occur.

Well it is in part "in the vertical", as any yaw will be with wings not level. I just find it odd that you want the student to associate the nose dropping from above the horizon to below the horizon with yaw. Since the aircraft spends most of its time wings level, I would have thought that the student naturally associates yaw with a heading change, and demonstrating that would be more compelling. It's also much more difficult for the student to tell the difference between the nose dropping through the horizon due to the pitch change that also occurs if you use DB6's method. Both result in the windscreen filling with more ground.

[Keygrip]

Yep - I'll buy that, too - but interesting edit to miss out the previous line about "relative to pilot".

[bookworm]

I'm sorry, I didn't mean to mislead by the omission. Yaw (as pitch and roll) are certainly relative to the pilot, but is that critical here? Isn't it just as easy to watch that prominent feature on the horizon moving from 10 o'clock to 2 o'clock as it is to watch the horizon moving in the windscreen (and try mentally to decouple yaw from pitch)?

[timzsta]

They way to teach this in the air is to demonstrate the primary effect of aileron - that it causes the aircraft to roll.

Then teach the primary effect of rudder, in that it causes yaw. What you have to show and explain here is yaw alone - ie you need to make use of crossed controls so the student only sees the yaw and not the secondary effect of yaw (roll).

Then show the secondary effect of roll which is yaw. This is not a level turn, which is where I went wrong to start of with on FI course. Just apply aileron and let the aircraft roll and then the yaw will follow.

Then demonstrate secondary effect of yaw which is roll but simply applying rudder alone.

Then do the further effect of roll and yaw which is spiral descent.

[MrAverage]

timzsta,

Finally a post to this subject that I can agree with. Simple, straightforward and easy for the student to see and understand.

I always mention the slip/skid at the appropriate moment during the demo (with the main emphasis on the roll/yaw) but doubt all but the gifted see it. Like JulieFlyGal, in my early years instructing I had trouble "eyeballing" the detail myself. Make things too complex and the average student (let alone the lowest common denominator) will neither see, understand nor remember the point. The intracacies are best left in the ground brief with the model.

Ask the average PPL holder what happens next after aileron input alone and he probably will struggle to answer correctly.

[toolowtoofast]

Haven't yet seen anyone say 'slow the aircraft down'.

Adverse yaw (initially) then yaw in the direction of the turn, as a secondary effect of aileron use, is a lot easier to see at 90kts, however, I would argue that one demo should show adverse yaw, then the NEXT one show secondary effect, as they are 2 different things, and need to be separated.

A demo that I do to show yaw (either adverse or secondary) as an effect of roll is roll 30deg side to side, with a pause of about 2 seconds at each side. Do this in balance. Then do it with feet on the floor. Then again in balance. The role of the rudder becomes obvious pretty quickly! This does have a dual component of adverse plus secondary though, and is more of a lesson in appropriate rudder use.

[spikeair]

I'm not an instructor , (a PPL holder) but when i was being taughtfor my IMC, the instructor showed me this.

POint the nose at a landmark on the horizon.
Bank left (no rudder) and watch the nose momentarily turn to the right before the aircraft turns left.

Repeat the excercise again this time with a bit of left rudder at the start of the turn and this time , the nose turns left striaght away.

Basically the point of the excercise was to empahise cooridnated turns and that passengers in teh back might pick up on it and so its more comfortable to use cooridinated turns with both stick and rudder.

[Troy McClure]

Adverse aileron yaw is the secondary effect of roll.

Rolling and then watching the nose drop sideways is the primary effect of gravity with a forward C of G, or if you like the secondary effect of having an angle of bank.

Roll left, aircraft yaws right. Don't let anyone tell you it will yaw left....

Pick a point on the horizon, roll left and right - nose yaws the opposite way. Practice compensating with rudder until you can keep that point on the horizon constant, then you're co-ordinating correctly.

[bArt2]

Go to a safe altitude

Fly slow, as the effect of adverse yaw is higher at slow speed. (I use 60 KIAS in the C152).

Use higher than normal roll rates as the effect will also be bigger.

Tell him that you are exagerating on the control to show him the effect.

roll the aircraft at a rather positive rate to about 45º bank, and tell the student to look to the ball, it will go allmost full deflection to the other side,and the slowly comes back. Furthermore the effect is so big that most of the students will defenitely feel it. Ask him if he feels the sideways force.

Then do the same but use the rudder to keep the ball centered.

And tell him to feel the controlls while you are using the rudder, so he gets a feel of how much to use.

Watch out with students that get sick easily :}

Bart

[1Bingo]

Blah, blah, blah

[DB6]

Dear dear. Troy, your statement "Adverse aileron yaw is the secondary effect of roll." is 100% incorrect, and if you are an instructor what you are teaching is fundamentally wrong and betrays a worrying lack of understanding. Adverse yaw has bugger all to do with roll, it is purely a result of aileron operation. Sorry if that appears insulting but if you are teaching that you really need to get it sorted out.
To all others banging on about adverse yaw, go back to post 1 and RTFQ.

[Troy McClure]

Ok, fair point: adverse yaw is the secondary effect of aileron, not of roll.

I still maintain that a slip leading to yaw is a result of angle of bank, not of roll. For example. if you're rolling from 45º left wing down to 10º left wing down (ie rolling right), the slip and therefore the yaw is still to the left throughout (aided dare I say by a bit of adverse aileron yaw also to the left).

Begging the question, is there a secondary effect of roll at all?

[Oktas8]

Airbus38 - I agree with you. The way it's taught (which is the way I teach it too!) does seem a little futile. It involves deliberately mishandling the controls, and why would we do this at such an early stage of training? Much more important to demonstrate combined use aileron & rudder for adjusting bank angle - which we do in a later lesson.

As an aside - I don't say "further effect of roll". I use "further effect of bank" - because slip is a function of bank angle not of roll rate. But that doesn't contribute to the original post I'm afraid. :\

[noprobs]

Well, now that we've got that sorted out, and glossed over the simple matter of what happens after you apply rudder to produce a yawing motion, let's just take a step back to think about different types of aircraft.

First, I seem to remember 2 different demonstrations in the Hawk. At a high angle of attack, it was pretty much like the light aircraft case. But at a low angle of attack, the differential wing lift was not as apparent as the force produced by the fin and rudder. The increased lift acting above the roll axis caused the aircraft to roll opposite to the applied rudder. Interesting, obvious, but ultimately useless knowledge. Send for an A cat QFI.

Then there was the Jaguar. With no ailerons, just spoilers and a differential tailplane ("tailerons") it made your head hurt to think what was happening in a turn. As to the logic of destroying lift to achieve roll, when you have little lift to start with, even if you do avoid adverse yaw .... What's more, there was the spine-bending compensation of automatic rudder application at high-G high AoA.

With the Harrier, things were fairly conventional until you used reaction controls as well as aerodynamic controls. There has recently been a long discussion on the Mil thread about the dangers of going sideways, and why the roll reaction controls can blow both up and down. But how about going backwards, when the all-flying tail operates in the opposite sense (ie stick back = nose down), and opposes the reaction controls?

Sorry, I digress, but there's always something new and interesting in aviation, and you did start by asking how one thing leads to another. Always consider the consequences. :confused:

[1Bingo]

Rudders on an Eagle have quite an effect at high AOA, and there are two of them. Again, the whole concept of high AOA and rudder effectiveness is meat enough for lengthy discussion.

Then there is automatic yaw damping for the more muted flight regimes and platforms, in which case if it's working, we don't give a hoot about yaw due to roll.

Bingo

[john gratton]

Yaw, pri eff of rudder, is a sideways movement of the nose towards a wing-tip. For further eff of ail, apply small amount of ail and KEEP IT APPLIED. As the a/c rolls, the nose drops below the horizon. When banked, this downwards movement is towards the wingtip is therefore YAW. QED! Important, warn the student that you will roll to around 45deg bank, but don't worry, it's brief and not at all uncomfortable.
Also only apply small ail, otherwise you won't have time to get the words in without reaching worrying angle of bank. :)

[nick14]

I was under the impression that the nose drop due to bank was because you have inclined the lift vector from the vertical and so get an apparant reduction in lift, therefore nose drop...:confused:

Nick

[john gratton]

Having demonstated the further effect is roll, bring in the "so what" factor, or "need to know" i.e. "Why does this matter?" The only time the further effect is used in practical flying is in the negative sense, as part of stall recovery when a wing has dropped. So here we have

CC forward - to unstall the wings
Full power
Ailerons neutral - because using them WHEN STALLED can aggravate
wing drop
Rudder - to prevent further wing drop (i.e. yaw/roll)
THEN when wings are unstalled, roll wings level (lots of ail and rudder to balance) and pull out.

Unless you include this, the further effect demo remains academic and
a waste of time. Hope this helps. John Gratton

[JugglingSpence]

Hey, I'm a PPL student, at the moment I'm reading Principles of Flight and have just found a way of remembering (or demostrating for instructors) the secondary effects of roll and yaw...

Basically all you need to do is move your head to one side, if you yaw your head to the right your neck bends in a way that rolls your head to the left. If you roll your head to the right then you will see your chin yaws to the left.

I hope this helps, it's certainly worked for me. If it's wrong please let me know as I may have misunderstood something, either that or I have a major problems with my neck!

[eyeinthesky]

The secondary effect of yaw (roll) can be of great use to students when they move onto navigation.

I defy almost any student to keep the aircraft straight & level whilst holding the control wheel and looking down at their PLOG or chart. Most will involuntarily put pressure on one side of the column as they look down, resulting in a roll (usually to the left if they are using their left hand).

I teach students to ensure the aircraft is trimmed for straight and level, and then take their hand off the control column but leave their feet on the rudder pedals. The aircraft is inherently stable and should not deviate significantly during the time it takes to fill in a PLOG, plan a diversion or consult a chart. Any slight deviations can be corrected using the rudder to use the secondary effect of yaw to 'pick up' a downgoing wing. Most students find this works really well. In smooth air, some can fly for up to 10 mins without having to use the control column.

[shdw]

I have only skimmed through this so my apologies if I repeat a couple things. I just stumbled upon this post while preparing an advanced aerodynamics lesson for my students and realized one thing, there is allot of confusion between rudders and ailerons.

First I want to start by saying; it is called proverse roll and adverse yaw. It is not and has never really been secondary effect and in today’s aircraft effects from aileron yaw in the wind is drastically reduced. These are all just fancy new terms to make it sound easier to understand which does nothing but confuse those that actually understand it. If you want proof go turn your ailerons to full deflection in either direction, note the aileron deflects up more than down (you will understand why soon). So my advice is to ignore even discussing this with your student as its effects are minimal.


Adverse yaw (induced drag)

So now how does adverse yaw work? Well you turn the aircraft lets say to the right what happens? The left wing rises and the right wing falls, the rising (left) wing is now producing significantly more lift than the falling right wing. We have certainly taught our students by now that induced drag is drag created by lift (if not this would be a great time). So the left wing now producing more lift and drag will get pulled backwards by that drag causing the nose to rise to the left showing that you need right rudder to correct.

To answer the first question from the paragraph above, we have adverse yaw because of uneven lift causing uneven drag on each wing. A model with strings representing forces attached to the wings gives a great on the ground visual before the flight demonstration.


Adverse yaw (parasite drag)

Now you are in the turn, take your feet off the rudders and increase that turn (cfi do this) to 45-60 degrees and look at the inclometer (the ball). Notice it is still deflected to the to the right (still using the right turn from above) indicating you need right rudder. You might think, well I already handled the yaw do to rudder so why is my aircraft yawing again.

To answer this go outside have your student grab onto a near by poll (telephone poll, lamp post, etc) and hold one arm out and walk around the poll. Explain how the outside arm travels a farther distance than the inside arm and must therefore go faster. Now relate this to your aircraft in a turn and how parasite drag on the higher (left) wing will be greater because it is traveling faster than the right wing. Therefore parasite drag is the reason for needing continuous rudder through turns (especially steeper turns as the steeper the turn the greater the differential).

This here is also why the ailerons are deflected more up than down. By deflecting more up the aileron on the inside wing of a turn will create more drag attempting to offset adverse yaw effects.


Proverse roll

You push on that right rudder and the nose shifts right then seconds later the right wing drops and you start turning right. This happens simply because of the right wing being on the inside of a now skidding turn (great way to demonstrate slip and skid, skid is like what you see driving a car to explain it on a level your student might get) is moving slower then the left wing on the outside. So the faster moving left wing generates more lift and you are in a turn.


Conclusion of roll/yaw

As far as those two go that is all I would think to discuss with a new student a few lessons in. I also introduce this to my students starting at lesson 1; there is no better time to learn how and why your airplane does what it does than the first lesson. Too many people are making it through their private without knowing thoroughly how their aircraft flies.


Restatement of previous thoughts

As far as the names of them, if you want to use obscure names that are not recognized in the engineering world, fine. But the engineering side is much easier to teach than any of these obscure new and old names coming out. Teach the 3 forces, not 4, lift and drag are byproducts of aerodynamic force acting off the aerodynamic center, teach that.

We are taught in our CFI course to teach things right first because of primacy. So go study up on stability and control, everything in relation to aerodynamic force/center, center of pressure, coupled effects (dutch roll spiral divergence primarily), and learn how they work not only by themselves but together.


Why I feel this way - example

Draw on a piece of paper an airplane put a circle just behind the wing for cg and draw a line down for weight, then a circle just behind that (open circle) for aerodynamic center and draw a line diagonally back for aerodynamic force, and finally on the tail draw another circle and arrow pointing down for the tail down force. From this you can explain why the tail exhibits a down force, cause if it didn't the plane would just flip end over end all day. *Edited out missinformation: A far aft cg will not cause an end over end rotation. My apologies for any confusion this may have caused.* You can show how moving the cg aft decreases the work needed to be done by the tail down force allowing the aircraft to fly at a lower angle of attack which shows why it gets better performance and lower stall speeds at an aft cg. Hopefully I have made my point, learn this stuff and teach it, which is basic enough to teach to a freshman in high school, if their younger than that find a sea saw and I bet you can teach them.


Hopefully this wasn’t too lengthy for everyone if you want to know more please ask there are ways to break down every component of aerodynamics so that it can be taught even to someone who knows nothing about aircraft. Also here is just a starting point for what I think every instructor should know:

Click here:http://www.mypilotforum.com/phpBB3/download/file.php?id=53 for a link to download a power point presentation I did on aerodynamics. Obviously you can’t see all the background work I prepared to demonstrate all of it, but at least you can take it and use it as a starting point of what you should know about an aircraft. That is my own personal site all information is safe but please virus scan anyways as you should do with anything you download.

Good Luck

~Brian

[Lurking123]

Surely the aim of the lesson (in JAA land the very first lesson given after famil?) is to demonstrate that any application of aileron requires balancing with rudder? The way I was taught to demonstrate this was to pick a feature, then roll left and right in an 'oscillatory' manner. The nose would weave all over the place. Repeat by applying rudder in concert with aileron to keep the nose in the same place. From a student PPL's perspective we can argue about the finer points of adverse yaw vs. slip but all we are trying to achieve is a student who can recognise the need to maintain balanced flight.

Am I being too simplistic?

[shdw]

all we are trying to achieve is a student who can recognize the need to maintain balanced flight.

That is the problem, we spend time just showing them how to recognize a problem and not the why it happens. Instead we give scenario after scenario in an attempt to prepare our students for everything, but still no why.

If you take the time to teach the student the finer points of aerodynamics and why the aircraft flies certain ways and can't fly other ways. If you don't see this as an issue go look at how many accident reports happen from cross controlled stalls on landings. If those pilots knew why their aircraft flew they would know why it cannot fly in that fashion.

So we are arguing aerodynamics in the finer points and aspects because a thorough understanding of these principles can save your life. :) Good answer?

[Lurking123]

So are you advocating a thorough lesson in aerodynamics before the first instructional flight?

PS. I take issue with your statement:

If you want proof go turn your ailerons to full deflection in either direction, note the aileron deflects up more than down (you will understand why soon).

I have flown a number of types (and indeed teach on a type) where that is simply not the case.

[shdw]

First,
I have flown a number of types (and indeed teach on a type) where that is simply not the case.

This is not the case on some aircraft I believe before the 70s but I do not hold me to that one I would have to look that up. But newer aircraft, all new Cessna and new pipers use enough for it to be visible to the naked eye. Some older models may have a small degree of difference but it might go unnoticed if not measured.

EDIT: I direct you here: Adverse yaw - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Adverse_yaw) for further information on differential ailerons.


On the other note, I am advocating that as you go through the lessons you introduce pertinent aerodynamic principles on the ground that occurs in the maneuver. When you teach a stall spend 30 minutes on the ground explaining how it is happening and why. Same with weight and balance and talks of CG you can bring up the model from my original post. Simply broaden your student’s horizon for each beginning lesson, that way they truly understand their aircraft.

[hugh flung_dung]

Hmm, in an earlier thread (steep turns) we had JulieFlyGal paired with Pugilistic Animus, now we have JulieFlyGal paired with a new member called shdw, who has similar characteristics to PA. I don't really care but I do (slightly) wonder why people play these games.

Ah well, back to the real world: teach what the stude needs to know to be safe, and follow the KISS principle

HFD
(edited to fix typo)

[shdw]

we had JulieFlyGal paired with Pugilistic Animus

Well I went back to see who this person was, but I don't even see posts. Sorry if I my beliefs match someone else’s, they should, they are right.

Anyways who I am isn't the point; the point is there are even instructors that are lost when it comes to even basic aerodynamics. You would think something as simple as basic aerodynamics topics like controling coupling effects should be understood by every instructor and every instructor should teach it accordingly and properly to their students.

I would be please if you could show me something that I said that was wrong in my post because if there is something I sure would like to know. Like many others here I am nothing more than an instructor trying to pass on knowledge and pick up what knowledge I can when I can. On one last note, I only came on here to post because I couldn't find a single message on here explaining these effects properly and I believed that should be fixed.

[Lurking123]

shdw, thanks for the Wiki link, it will supplement my ATPL notes. ;)

[shdw]

No problem Lurking though I have no clue what ATPL is, I am from the states so I am guessing ATPL is a European aviation course?

[Pugilistic Animus]

Hmm, in an earlier thread (steep turns) we had JulieFlyGal paired with Pugilistic Animus, now we have JulieFlyGal paired with a new member called shdw, who has similar characteristics to PA. I don't really care but I do (slightly) wonder why people play these games.No, I'm not JulieFlyGirl or Shdw, I agree with him

just to add you don't need much theory 'stick and rudder, the FAA airplane flying handbook and FAA pilot''s handbook of aeronautical knowledge is fine....So make false accusation somewhere else :*

edit: you talk a lot of horse SH:mad:IT!!!


Lester:E

Unless you yourself can come up with a few solutions to the Karman T'sien integral

Ah well, back to the real world: teach what the stude needs to know to be safe, and follow the KISS Como No!

[shdw]

FAA airplane flying handbook and FAA pilot''s handbook of aeronautical knowledge is fine

No offense Lurking, just trying to make an example.

I have flown a number of types (and indeed teach on a type) where that is simply not the case.

If there are instructors out there without this sort of knowledge of their aircraft, a basic effect that causes serious issues than I don't think that basic knowledge is enough.

I was originally going to tell you all these great reasons why this knowledge is priceless to any student, and then I realized I have a story that might prove more beneficial. This actually happened to me today in a Cessna 152 with a student post-solo going on our second cross country. He hasn't had my aerodynamic lessons (I give them on those lessons after solo x-country before private).

So we lift off runway 10 with wind about 10 knots x-wind gusting in the teens. About 200 feet off the ground we hit a crossing section of air that yawed the aircraft about 60 degrees and slowed our airspeed to just under 60 knots (well above stall but dropping fast) in about 4 to 5 seconds. My student, like many in a situation like this completely froze with an aircraft rapidly slowing in a sharp yawing motion to the left 200 feet AGL. After seeing airspeed drop below 55 now with him frozen and now just saying Brian...Brian (noticably scared by this unusual attitude), at that point I took the aircraft stomped on the right rudder and dropped the nose 15-20 degrees. It took full right rudder to stop the rotation and had a situation like this not been dealt with promptly you would have been reading about it on the news and not on these forums.

On a side note, to anyone who just read that, if you thought right aileron + nose down would work you might have been on the news too. Applying right aileron before pushing the nose down would have drastically increased the angle of attack of the lower (left) wing which would have likely stalled that wing and inevitably put you in a spin.

Anyways that is my two cents, I thank my college for giving me a full aerobatics and advanced aerodynamics class (second semester right after you get your license). I don't know how I would have reacted to that if I hadn't had extensive spin/aerobatic training.

Thanks again for dealing with my ratings(EDIT: raNtings)!

Lurkin - damn smart a** lol

~Brian

[Lurking123]

Was that 'ratings' or 'rantings'? :)

[Imp462]

Many of the old military instructors, of which I am one, will disagree with me because it has been drummed into us for years that the secondary effect of aileron is yaw. Ignore adverse aileron yaw for now as we all know what causes that. During S&L, apply left aileron with the feet off the rudders. The aircraft rolls to the left and then PITCHES down. How do we correct it? Obviously with elevator.
If the secondary effect was a yaw to the left, we would then be compelled to correct it by applying right rudder. This is clearly not the case.
If one applies left aileron and then observes the ball, one would notice that it hangs slightly into the turn thereby requiring a little left rudder to centre it. Therefore, it a left hand turn, one applies left aileron, left rudder and up elevator as we all know.
Why do we have to keep telling students that the secondary effect aileron is yaw but it needs to be corrected with elevator? No wonder the cadets, and instructors, are confused.